Flat panel display has many advantages such as thin body, power saving, no radiation, and has been widely used. The existing flat panel display devices mainly include a liquid crystal display (LCD) and an organic light emitting display (OLED). A thin film transistor (TFT) array is an important part of a flat panel display device and can be formed on a glass substrate or a plastic substrate, so as to function as a light-open device and a driving device used in an LCD or OLED for example.
FIG. 1 is a schematic structural diagram of a typical conventional thin film transistor array substrate. As shown in FIG. 1, the thin film transistor array substrate comprises a base substrate 1, a buffer layer 2, an active layer 3, a gate insulating layer 4, a gate layer 5, an interlayer dielectric layer 6, a source/drain layer 7, a planarization layer 8, and a pixel electrode layer 9. The thin film transistor is mainly composed of the active layer 3, the gate insulating layer 4, the gate layer 5, the interlayer dielectric layer 6 and the source/drain layer 7. In order to prevent affection to the performance of the thin film transistor due to ions contained in the base substrate or water and oxygen generated during a manufacturing process, as shown in FIG. 1, the buffer layer 2 is provided on the base substrate 1 first, and then each layer of the thin film transistor is formed on the buffer layer 2. A high density SiNx is used as the material of the buffer layer 2, but it results in a loss of transmittance of the array substrate.
With an increase of the resolution of the display, the traditional methods to improve the transmittance or brightness of the display panel by means of improving an aperture ratio, a color-resist transmittance, backlight brightness, liquid crystal efficiency and the like, have gradually faced bottlenecks. How to improve the transmittance rate of the array substrate without reducing electrical performance becomes a key technical problem.